In current production printers, the solid color of each separation (primary) is controlled based on the achievement of a nominal DMA (developed mass per unit area) as measured on the photoreceptor (usually a belt or drum). Typically, reflectance measurements are made using an optical sensor, e.g., an ETAC (enhanced toner area coverage) densitometer, to infer DMA via a model relating the two, i.e., mass as a function of reflectance and a target DMA is determined by substituting the nominal DMA into this model. Then, while printing, measuring the reflectance of patches in the inter-document zone, xerographic process control loops adjust the xerographic actuators such that the reflectance tracks the target value. Examples of common xerographic actuators include ROS (raster output scanner) exposure, the photoreceptor voltages (charged and/or discharged voltage), donor and/or magnetic roll voltages, and toner concentration. Although functional, this type of process control system, presently used on iGen3 and iGen4 systems, is subject to color variation due to variation in the environment, media, sensors, xerographic processes, operating conditions, downstream effects from transfer & fusing, etc.
Accordingly, what is needed in this art are increasingly sophisticated systems and methods for xerographic Dmax control which is based upon measurements using an inline spectrophotometer (ILS) or similar device to increase color stability and gamut mapping robustness.